1. Field of the Invention
The present invention relates to an eye-tracking driving system, especially to an eye-tracking system controlled by the user's eye. It not only utilizes the unique eye-controlled method, but also will not contact the user's eyes or skin. It is suitable for the disabled persons or the elderly so that they can drive a powered vehicle easily.
2. Description of the Prior Art
Due to the rapid development of medical technology, the life of a human is significantly prolonged. The death rate decreases. The averaged age of whole society gradually moves up. Accordingly, many problems such as medical care for disabled persons and the elderly occur. In Taiwan, the elderly was over 7% of the population in 1994. In September of 2000 the elderly (age above 65) became 1.9 million which is 8.6% of the total population. In addition, the registered physical disabled and mental diseased persons in the end of 2000 were 711,064 persons. In which, 306,169 persons are the physical disabled persons. For those persons (disabled persons and the elderly), they can not walk or run like a normal person. So, the powered wheelchair or the mini electric tricycle will be the most reliable auxiliary equipment for transportation.
A general powered wheelchair is controlled by a joystick-like device. Except the joystick-like input device, there are at least two other methods to control, such as the head-gesture control and mouth-blowing control. However, for some seriously disabled persons, all these devices mentioned above are not suitable. So, the eye control (or eye-tracking control) might be the last available choice.
With regard to the eye-tracking research, it can be traced back to the nineteen century. However, all the existing eye-tracking methods can be classified into the following three types.
(1) The Limbus tracking method. Basically, it utilizes a light projects into the eyeball and then reflect from the eyeball. And, it has a video camera to capture the image around the eyeball. By analyzing the variation of the reflected light from the eyeball to determine the moving direction of the eyeball. The disadvantage of this method is that the upper boundary and the lower boundary of the eyeball often block by the upper eyelid and lower eyelid respectively. In addition, its resolution is very low. Plus, its initial calibration procedure is quite lengthy (to check nine points shown on the screen three times). Besides, the distance between the head and the video camera must be remained fixed. Thus, it is impossible to use it for long time.
The electro-oculography (EOG) method. The researcher attaches several electricity sensors (or electrodes) around the skin of the eye. This electro-oculography (EOG) technology detects eye movements from the electrical measurement of the difference in potential between the cornea and the retina. Essentially, eye movements are accompanied by the appearance of electric signals. In the front of the head, the corneal to potential creates an electric field, which changes in orientation as the eyeball rotates. Electrodes placed around the eye can detect these electrical signals. For example, when the eye moves to the right, a positive voltage difference is measured. If the eye moves to the left, another negative voltage difference is measured. Hence, it can determine the eye's moving direction. However, sweat might affect the electrical signal read out. So the signals become unstable and unreliable. In addition, the electrodes are adhered on the skin of the user, so it limits its practical application.
(3) The coil search method. A tiny coil is sandwiched by a pair of contact lens. A magnetic field is created around the eyeball. Once the eyeball rotates, the movement of the contact lens with the coil can be observed after signal processing. But, it is not suitable for wearing such contact lens too long. This kind of contact lens might injure the user.
Therefore, it is desired to develop a new powered vehicle that is controlled by a new eye-tracking system.